1. Field of the Invention
This invention generally relates to an electrochemical sensor for analyzing a liquid sample, and more particularly to an electrochemical sensor capable of measuring viscosity of a liquid sample.
2. Description of the Related Art
Electrochemical biosensors have been widely used to determine the concentrations of various analytes in liquid samples, e.g. blood and urine. There are already various electrochemical biosensors, e.g. blood glucose biosensors, cholesterol biosensors, uric acid biosensors and lactic acid biosensors, on the market. In particular, blood glucose biosensors are in widespread use and have become daily necessities for diabetics. Generally, a blood glucose biosensor is formed in a strip shape and uses at least two electrodes, e.g. a working electrode and a counter electrode, for generating an electrical signal, which is proportional to the amount of glucose in a blood sample, and transmitting the electrical signal to a blood glucose meter for showing the blood glucose level.
In recent years, there are many companies, e.g. Roche, LifeScan (Johnson & Johnson), Bayer, TheraSense and MediSense (Abbott), producing blood glucose biosensors and meters such as Roche's Accu-Chek, which is the largest market share, LifeScan's OneTouch, TheraSense's FreeStyle and MediSense's Precision. These products require only a blood sample of less than 3 microliters and take only around five to fifteen seconds to show a reading corresponding to the glucose level in the blood sample. However, none of these products can measure viscosity of a blood sample.
In many researches and clinical practices, it has been presented that many diseases such as high blood pressure, heart attack, coronary heart disease, myocardial infarction, diabetes, malignancy, and chronic hepatitis, etc., are all related to elevated blood viscosity. Accordingly, blood viscosity has become an important index for monitoring disease progression.
In the prior art, blood viscosity can be measured by a blood diluting pipette. However, the blood diluting pipette generally requires a blood sample of at least 1 cc or even more and takes at least six minutes or even more to obtain the viscosity of blood. Further, this blood sample of at least 1 cc can only be obtained from a patient, for example, using a needle and syringe to obtain a useful sample volume. Therefore, these procedures are inconvenient and often painful for the patient, particularly, when frequent samples are required.
In addition, various viscometers can be commercially obtained from the market. However, these viscometers still require at least a liquid sample of several hundred microliters or even more to obtain the viscosity.
Accordingly, the present invention provides an electrochemical sensor capable of measuring viscosity of a liquid sample with a small sample volume.